1. Field of the Invention
This invention relates generally to communication systems, and, more particularly, to wireless communication systems.
2. Description of the Related Art
Conventional wireless communication systems use a network of base stations to provide wireless connectivity to one or more mobile units. In some cases, the mobile units may initiate wireless communication with one or more base stations in the network, e.g., when the user of the mobile unit would like to initiate a voice or data call. Alternatively, the network may initiate the wireless communication link with the mobile unit. For example, in conventional hierarchical wireless communications, a server transmits voice and/or data destined for a target mobile unit to a central element such as a Radio Network Controller (RNC). The RNC may then transmit paging messages to the target mobile unit via one or more base stations or node-Bs. The target mobile unit may establish a wireless link to one or more of the base stations in response to receiving the page from the wireless communication system. A radio resource management function within the RNC receives the voice and/or data and coordinates the radio and time resources used by the set of base stations to transmit the information to the target mobile unit. The radio resource management function can perform fine grain control to allocate and release resources for broadcast transmission over a set of base stations.
A conventional base station provides wireless connectivity within a geographical region that is referred to as a cell, a macrocell, and/or a sector. Conventional base stations can transmit signals using a predetermined amount of available transmission power, which in some cases is approximately 35 W for a base station. The range of the macrocell is determined by numerous factors including the available transmission power, angular distribution of the available power, obstructions within the macrocell, environmental conditions, and the like. For example, the range of a macrocell can vary from as little as 300 m in a densely populated urban environment to as much as 10 km in a sparsely populated rural environment. The coverage area can also vary in time if any of these parameters changes.
One alternative to the conventional hierarchical network architecture is a distributed architecture including a network of access points, such as base station routers, that implement distributed communication network functionality. For example, each base station router may combine RNC and/or PDSN functions in a single entity that manages radio links between one or more mobile units and an outside network, such as the Internet. Base station routers wholly encapsulate the cellular access technology and may proxy functionality that utilizes core network element support to equivalent IP functions. For example, IP anchoring in a UMTS base station router may be offered through a Mobile IP Home Agent (HA) and the GGSN anchoring functions that the base station router proxies through equivalent Mobile IP signaling. Compared to hierarchical networks, distributed architectures have the potential to reduce the cost and/or complexity of deploying the network, as well as the cost and/or complexity of adding additional wireless access points, e.g. base station routers, to expand the coverage of an existing network. Distributed networks may also reduce (relative to hierarchical networks) the delays experienced by users because packet queuing delays at the separate RNC and PDSN entities in hierarchical networks may be reduced or removed.
At least in part because of the reduced cost and complexity of deploying a base station router, base station routers may be deployed in locations that are impractical for conventional base stations. For example, a base station router may be deployed in a residence or building to provide wireless connectivity to the occupants of the residents of the building. Base station routers deployed in a residence are typically referred to as home base station routers or femtocells because they are intended to provide wireless connectivity to a much smaller area (e.g., a femtocell) that encompasses a residence. Femtocells have a much smaller power output than conventional base stations that are used to provide coverage to macrocells. For example, a typical femtocell has a transmission power on the order of 10 mW. Consequently, the range of a typical femtocell is much smaller than the range of a macrocell. For example, a typical range of a femtocell is about 100 m. Clusters of femtocells may also be deployed to provide coverage to larger areas and/or to more users.
The functionality in a femtocell is typically quite similar to the functionality implemented in a conventional base station router that is intended to provide wireless connectivity to a macro-cell that may cover an area of approximately a few square kilometers. A femtocell may therefore be deployed by a service provider as an integral and trusted part of a wireless network, in which case the femtocell basically operates as a base station router with a relatively small range. However, femtocells may alternatively be designed to be inexpensive plug-and-play devices that can be purchased off-the-shelf and easily installed by a lay person. This type of femtocell, which is often referred to as a home femtocell or a home node-B, is not considered an integral or trusted part, of the wireless network because it is not deployed or controlled by the service provider and is therefore vulnerable to hacking and other unauthorized uses.
Home femtocells are typically connected to the outside network using the user's existing home network infrastructure, such as a cable modem or a DSL connection, A wireless service provider may therefore provide wireless connectivity to subscribers connected to the home femtocells over an air interface that implements 3G and/or 4G wireless access technologies. The wired or wireline home network infrastructure that provides the backhaul network that connects the femtocell to the wireless network. The home network infrastructure can be supported by the same service provider that provides wireless connectivity via the home femtocell or by a different service provider. For example, in some states Verizon operates both a wired network and a wireless network, whereas in other states Verizon only operates a wireless network and contracts or negotiates with other service providers to supply the wired network infrastructure.
When a mobile unit or user equipment (UE) connects to the femtocell, a policy server in the wireless network receives a request for service and decides whether to admit the new request. The admission decision is to be made based on a quality-of-service (QoS) profile associated with the subscriber and the new service flow is admitted only when the radio access network has sufficient available radio resources to support the requested quality-of-service. Wireline service providers also provide a variety of mechanisms to ensure QoS in the wireline access network such as fixed allocation of resources to a fixed line port, IETF defined DiffServ, DSCP marking, Ethernet TOS and TISPAN or ITU T defined policy and charging controls that support, dynamic QoS. However the wireless network is not aware of the availability of resources in the wired backhaul network. For example, current 3GPP standards and/or protocols do not differentiate between femtocells that are deployed by a service provider as conventional (trusted and secure) base station routers and femtocells that are deployed by individual as (mistrusted and insecure) home femtocells. Conventional wireless communication systems may therefore manage all femtocells as if they are deployed by a service provider as conventional (trusted and secure) base station routers. Consequently, there is no coordination between the wireless and wireline networks for the admission of/resource allocation for new and/or modified femtocell flows.